Appliance Repairs in PE - Transistors

Appliance Repairs in Port Elizabeth

Defy Refrigerator Electronic Thermostat - Front and Backside


WAIT! Wait come back! This information CAN be useful and will give you a better understanding of HOW all your gadget and Stuff work.

A transistor works like a water tap in your home, by which you control the flow of the water by opening and closing the tap – in other words a Transistor is a device that uses small changes in voltage to switch things on and off

There are different kinds of transistor but because I do not want to frighten you completely, I am going to tell you about the most common or most famous transistor found all over in your everyday life.

The N-channel Mosfet

This Item has a curvy top and solute square bottom with three legs. No-Yes, I think a drawing is going to be a better explanation

The mosfet has three legs and when you look at it, the silver plate should face away from you. The legs are called Gate, Drain and Source.

The Gate (left side) is where the current enters and the Gate also turns the transistor on and off.

The middle leg is called the Drain and is connected to the negative side of your load (load meaning Remote gates, TV, Fan, Washing Machine, Refrigerator, Sound System, Dishwashers, Vacuum Cleaners, Food processors, Mixers, Liquidizers and the list just goes on and on)

The Source is found on the right and this is where the power goes out. The source is also connected to the circuit ground
O!.... you are still here! - Obviously there is no Game on.

The Big scheme of Things

Now I am going to tell you how all this comes into play in your world. We can use the remote gate an example but since I was a teenager (long-ago) I wanted a remote for my bedroom lights. So using that example..

1. As mentioned previously the Drain should be connected to the negative of the light
2. The Positive of the external power supply (batteries of transformer) must be connected to the positive side of your lamp (load).
3. The Gate now controls if the lamp goes on or off. VOLLA! Simple and straight forward.

Sorry just one more ietzi bitzi snag - If the Gate controls the load, who is controlling the Gate. We are not going into politics where your need a controller to lookout for the controllers and those controllers again need other controllers who needs.,,, round and round we go.

Getting back to our light and N-channel Mosfet, we now need something to signal voltage into the Gate so that the light can switch on or off.
The first that spring to mind is a Mercury vibration switch which turns the light off when you lay down on your bed or a motion sensor switch that turns the power on when you walk past.

At this stage I will give you some useless more information if you are just an average person who wants to increase their general knowledge about how their gadgets work

• At the Gate of the N-channel Mosfet the voltage should always be less than 15Volts DC
• The Drain side can go up to 60 Volts

Now if you are still wondering why I gave you this information then read on but first I must give thanks to the guys from Eskom (power company) for providing work for us small people.

POWER SURGES – when more power move into your transistors than what it was build for it blows
Before wearing you out completely I will save the adding of a relay and more resistor for a next post

PS. I’ve never build my own bedroom remote switch which I thought would be a smooth move to have in my youth but now as I get older it seems it is going to a necessity.